Alkaline zinc-iron plating bath

ABSTRACT

The alkaline zinc-iron plating bath according to the present invention includes a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent, in which the complexing agent is an aliphatic compound having five or more hydroxy groups. When the aliphatic compound having a chain structure and five or more hydroxy groups is used as the complexing agent, for example, due to an inhibitor effect thereof, redissolution of a deposited plating film is prevented; and as a result, a thick plating film can be efficiently formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2020/046345, filed on Dec. 11, 2020, which designates the United States and was published in Japan, and which based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-223613, filed on Dec. 11, 2019, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to an alkaline zinc-iron plating bath that includes a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent.

BACKGROUND

In an alkaline zinc plating bath, current efficiency is generally low, and especially in an alkaline zinc-iron plating bath, the current efficiency is very low. This is because electrolytic deposition becomes less likely to occur since use of a complexing agent having a high complex stability constant such as triethanolamine is required in order to dissolve both zinc and iron in a highly alkaline bath at the same time. In the Patent Document described below, an example of an alkaline zinc-iron plating bath is described.

Patent Literature

Patent Literature 1: Japanese Examined Patent Publication No. S62-238387

SUMMARY

As described above, in an alkaline zinc-iron plating bath the current efficiency is very low. Accordingly, the present invention has an object to provide an alkaline zinc-iron plating bath having an improved current efficiency, that is, an alkaline zinc-iron plating bath capable of efficiently forming a thick plating film.

The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 1 to 9.

FIG. 2 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 10 to 13.

FIG. 3 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 14 to 17.

FIG. 4 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 18 to 21.

FIG. 5 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 22 to 25.

FIG. 6 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 26 to 29.

FIG. 7 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 30 to 33.

FIG. 8 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 34 to 37.

FIG. 9 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 38 to 41.

FIG. 10 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 42 to 45.

FIG. 11 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 46 to 49.

FIG. 12 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Examples 50 to 53.

FIG. 13 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Comparative Examples 1 to 6.

FIG. 14 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Comparative Examples 7 to 10.

FIG. 15 is the drawing that describes the raw materials of the alkaline zinc-iron plating bath of Comparative Examples 11 to 14.

FIG. 16 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 1 to 9.

FIG. 17 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 10 to 17.

FIG. 18 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 18 to 25.

FIG. 19 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 26 to 33.

FIG. 20 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 34 to 41.

FIG. 21 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 42 to 49.

FIG. 22 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 50 to 53.

FIG. 23 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Comparative Examples 1 to 6.

FIG. 24 is the drawing that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Comparative Examples 7 to 14.

FIG. 25 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 1 to 9.

FIG. 26 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 10 to 17.

FIG. 27 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 18 to 25.

FIG. 28 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 26 to 33.

FIG. 29 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 34 to 41.

FIG. 30 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 42 to 49.

FIG. 31 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Examples 50 to 53.

FIG. 32 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Comparative Examples 1 to 6.

FIG. 33 is the drawing that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Comparative Examples 7 to 14.

FIG. 34 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 1 and Comparative Example 1.

FIG. 35 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 2 and Comparative Example 2.

FIG. 36 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 3 and Comparative Example 3.

FIG. 37 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 4 and Comparative Example 4.

FIG. 38 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 5 and Comparative Example 5.

FIG. 39 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 6 and Comparative Example 6.

FIG. 40 is the graph that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 7.

FIG. 41 is the graph that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 8.

FIG. 42 is the graph that describes the thickness (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 9.

FIG. 43 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 10 and Comparative Example 7.

FIG. 44 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 11 and Comparative Example 8.

FIG. 45 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 12 and Comparative Example 9.

FIG. 46 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 13 and Comparative Example 10.

FIG. 47 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 14 and Comparative Example 11.

FIG. 48 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 15 and Comparative Example 12.

FIG. 49 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 16 and Comparative Example 13.

FIG. 50 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 17 and Comparative Example 14.

FIG. 51 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 18 and Comparative Example 1.

FIG. 52 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 19 and Comparative Example 2.

FIG. 53 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 20 and Comparative Example 3.

FIG. 54 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 21 and Comparative Example 4.

FIG. 55 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 22 and Comparative Example 7.

FIG. 56 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 23 and Comparative Example 8.

FIG. 57 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 24 and Comparative Example 9.

FIG. 58 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 25 and Comparative Example 10.

FIG. 59 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 26 and Comparative Example 11.

FIG. 60 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 27 and Comparative Example 12.

FIG. 61 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 28 and Comparative Example 13.

FIG. 62 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 29 and Comparative Example 14.

FIG. 63 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 30 and Comparative Example 1.

FIG. 64 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 31 and Comparative Example 2.

FIG. 65 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 32 and Comparative Example 3.

FIG. 66 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 33 and Comparative Example 4.

FIG. 67 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 34 and Comparative Example 1.

FIG. 68 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 35 and Comparative Example 2.

FIG. 69 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 36 and Comparative Example 3.

FIG. 70 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 37 and Comparative Example 4.

FIG. 71 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 38 and Comparative Example 1.

FIG. 72 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 39 and Comparative Example 2.

FIG. 73 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 40 and Comparative Example 3.

FIG. 74 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 41 and Comparative Example 4.

FIG. 75 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 42 and Comparative Example 1.

FIG. 76 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 43 and Comparative Example 2.

FIG. 77 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 44 and Comparative Example 3.

FIG. 78 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 45 and Comparative Example 4.

FIG. 79 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 46 and Comparative Example 1.

FIG. 80 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 47 and Comparative Example 2.

FIG. 81 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 48 and Comparative Example 3.

FIG. 82 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 49 and Comparative Example 4.

FIG. 83 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 50 and Comparative Example 1.

FIG. 84 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 51 and Comparative Example 2.

FIG. 85 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 52 and Comparative Example 3.

FIG. 86 is the graph that describes the thicknesses (μm) of the plating film at each current density (ASD) in the alkaline zinc-iron plating bath of Example 53 and Comparative Example 4.

FIG. 87 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 1 and Comparative Example 1.

FIG. 88 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 2 and Comparative Example 2.

FIG. 89 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 3 and Comparative Example 3.

FIG. 90 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 4 and Comparative Example 4.

FIG. 91 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 5 and Comparative Example 5.

FIG. 92 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 6 and Comparative Example 6.

FIG. 93 is the graph that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 7.

FIG. 94 is the graph that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 8.

FIG. 95 is the graph that describes the eutectic rate (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 9.

FIG. 96 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 10 and Comparative Example 7.

FIG. 97 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 11 and Comparative Example 8.

FIG. 98 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 12 and Comparative Example 9.

FIG. 99 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 13 and Comparative Example 10.

FIG. 100 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 14 and Comparative Example 11.

FIG. 101 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 15 and Comparative Example 12.

FIG. 102 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 16 and Comparative Example 13.

FIG. 103 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 17 and Comparative Example 14.

FIG. 104 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 18 and Comparative Example 1.

FIG. 105 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 19 and Comparative Example 2.

FIG. 106 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 20 and Comparative Example 3.

FIG. 107 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 21 and Comparative Example 4.

FIG. 108 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 22 and Comparative Example 7.

FIG. 109 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 23 and Comparative Example 8.

FIG. 110 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 24 and Comparative Example 9.

FIG. 111 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 25 and Comparative Example 10.

FIG. 112 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 26 and Comparative Example 11.

FIG. 113 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 27 and Comparative Example 12.

FIG. 114 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 28 and Comparative Example 13.

FIG. 115 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 29 and Comparative Example 14.

FIG. 116 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 30 and Comparative Example 1.

FIG. 117 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 31 and Comparative Example 2.

FIG. 118 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 32 and Comparative Example 3.

FIG. 119 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 33 and Comparative Example 4.

FIG. 120 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 34 and Comparative Example 1.

FIG. 121 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 35 and Comparative Example 2.

FIG. 122 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 36 and Comparative Example 3.

FIG. 123 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 37 and Comparative Example 4.

FIG. 124 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 38 and Comparative Example 1.

FIG. 125 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 39 and Comparative Example 2.

FIG. 126 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 40 and Comparative Example 3.

FIG. 127 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 41 and Comparative Example 4.

FIG. 128 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 42 and Comparative Example 1.

FIG. 129 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 43 and Comparative Example 2.

FIG. 130 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 44 and Comparative Example 3.

FIG. 131 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 45 and Comparative Example 4.

FIG. 132 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 46 and Comparative Example 1.

FIG. 133 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 47 and Comparative Example 2.

FIG. 134 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 48 and Comparative Example 3.

FIG. 135 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 49 and Comparative Example 4.

FIG. 136 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 50 and Comparative Example 1.

FIG. 137 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 51 and Comparative Example 2.

FIG. 138 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 52 and Comparative Example 3.

FIG. 139 is the graph that describes the eutectic rates (%) of iron at each current density (ASD) in the alkaline zinc-iron plating bath of Example 53 and Comparative Example 4.

DESCRIPTION OF EMBODIMENTS

The following description is the list of aspects of the embodiments of the present application.

In order to achieve the object described above, the alkaline zinc-iron plating bath of the present invention is characterized by that the alkaline zinc-iron plating bath includes a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent; and the complexing agent is an aliphatic compound having five or more hydroxy groups.

The alkaline zinc-iron plating bath of the present invention prevents redissolution of the deposited plating film because an aliphatic compound having five or more hydroxy groups is used as the complexing agent, for example, due to the inhibitor effect thereof, and therefore can form a thick plating film efficiently.

The “alkaline zinc-iron plating bath” described in the present invention is an alkaline zinc-iron plating bath that includes a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent; and the complexing agent is an aliphatic compound having five or more hydroxy groups.

Here, the zinc compound is, for example, ZnO; and the metal concentration of zinc is preferably 5 to 40 g/L. In addition, the alkali hydroxide is, for example, NaOH or KOH; and the NaOH content is preferably 30 to 200 g/L.

Moreover, the metal salt containing iron is, for example, Fe₂(SO₄)₃, Fe(SO₄)₇H₂O, FeCl₃, FeCl₂, or Fe(OH)₃; and the metal concentration of iron is preferably 0.02 to 20 g/L, while more preferably 0.1 to 10 g/L. Here, in order to efficiently form a thick plating film, the metal concentration of iron is preferably 1 g/L or more, while more preferably 3 g/L or more.

In the alkaline zinc-iron plating bath whose metal concentration of iron is 1.3 g/L or more, when a conventional complexing agent, specifically, triethanolamine, is used, the eutectic rate of iron varies greatly depending on the current density. However, when the complexing agent that is an aliphatic compound having five or more hydroxy groups is used, the eutectic rate of iron can be made almost constant independent of the current density. Specifically, for example, when the current density is within the range of 0.5 to 10 ASD, it is possible to reduce the difference in the eutectic rate of iron.

The aliphatic compound having five or more hydroxy groups may have a chain structure or a cyclic structure. Further, the aliphatic compound having a chain structure may have a linear structure or a branched structure.

Illustrative examples of the aliphatic compound include a pentose, a hexose, a monosaccharide, a polysaccharide, and a sugar alcohol. Illustrative examples of the aliphatic compound of the pentose include riburonic acid, arabinuronic acid, xylonic acid, lyxonic acid, ribitol, arabinitol, and xylitol. Illustrative examples of the aliphatic compound of hexose include allose, altrose, glucose, mannose, gulose, idose, galactose, talose, allonic acid, altronic acid, gluconic acid, mannonic acid, gulonic acid, idonic acid, galactonic acid, talonic acid, alluronic acid, altruronic acid, glucuronic acid, mannuronic acid, guluronic acid, iduronic acid, galacturonic acid, tartronic acid, allitol, altritol, sorbitol (glucitol), mannitol, iditol, and galactitol. Illustrative examples of the aliphatic compound of monosaccharide include psicose (allulose), fructose, sorbose, tagatose, allose, altrose, glucose, mannose, gulose, idose, galactose, talose, fucose, fuculose, rhamnose, and sedoheptulose. Illustrative examples of the aliphatic compound of polysaccharide include sucrose, lactose, maltose, trehalose, turanose, cellobiose, raffinose, melezitose, maltotriose, acarbose, stachyose, fructooligosaccharides (FOS), galactooligosaccharide (GOS), mannan oligosaccharide (MOS), lactose fructose oligosaccharide, glycogen, starch (amylose-amylopectin), cellulose, dextrin, glucan (β1,3-glucan), fructan (inulin-levan β2→6), and chitin. Illustrative examples of the aliphatic compound of the sugar alcohol include D-arabinitol, L-arabinitol, xylitol, ribitol (adonitol), D-iditol, galactitol (dulcitol), D-glucitol (sorbitol), mannitol, volemitol, and perseitol.

In the alkaline zinc-iron plating bath, the molar ratio of the metal containing zinc and iron to the complexing agent is preferably 1:0.5 to 1:5. It is particularly preferable that the molar ratio of the metal containing zinc and iron to the complexing agent is 1:1 to 1:3. Further, when the molar ratio of the metal containing zinc and iron to the complexing agent is made 1:3, in the alkaline zinc-iron plating bath with the metal concentration of iron being 1.3 g/L or more, for example, the difference in the eutectic rates of iron can be made to 8% or less in the current density of 0.5 to 10 ASD.

EXAMPLES

Hereinafter, the present invention will be described more specifically by showing Examples. However, the present invention is not limited to these Examples, and may be implemented with the embodiments variously changed and modified in accordance with the knowledge of those skilled in the art.

Using each raw material with the formulation described in FIG. 1 to FIG. 15 , the alkaline zinc-iron plating baths of Examples 1 to 53 and Comparative Examples 1 to 14 were prepared. The details of each raw material are as follows.

Caustic Soda (NaOH): manufactured by Tokuyama Corporation.

Zinc oxide (ZnO): manufactured by Hakusui Tech Co., Ltd.

Ferric sulfate (Fe₂(SO₄)₃) solution manufactured by JUJO Synthetic Chemistry Labo.

Ferrous sulfate heptahydrate (FeSO₄.7H₂O): manufactured by FUJIFILM Wako Pure Chemical Corporation.

Ferric chloride (FeCl₃) solution: manufactured by Hiei Co., Ltd.

Additive A: Metasu AZ-GM2; manufactured by Yuken Industry Co., Ltd.

Additive B: Metasu AZ-GH2; manufactured by Yuken Industry Co., Ltd.

Sodium gluconate: manufactured by Fuso Chemical Co., Ltd.

Xylitol: manufactured by FUJIFILM Wako Pure Chemical Corp.

Sorbitol: manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.

Mannitol: manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.

Glucose: manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.

Fructose: manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.

Lactose: manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.

Maltose: manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.

Triethanolamine TEA90; manufactured by Mitsui Chemicals, Inc.

The alkaline zinc-iron plating bath of the above-described raw materials is prepared as follows. Namely, first, a complexing agent (sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, maltose, or triethanolamine) is dissolved with water of about 40% of the total volume, and then, a metal salt containing iron (ferric sulfate solution, ferrous sulfate heptahydrate, or ferric chloride solution) is added thereto, followed by stirring this for about 2 hours. Thereby, an iron ion-containing liquid is prepared. Next, a liquid in which caustic soda and zinc oxide are dissolved with water of about 20% of the total volume is added to the iron ion-containing liquid, followed by stirring this for about 2 hours. Finally, water is added so as to reach the total volume, followed by stirring this for about 20 hours. Thereby, the alkaline zinc-iron plating bath is prepared.

During preparing the alkaline zinc-iron plating bath of Comparative Example 3, when the ferric sulfate solution was added into the complexing agent (triethanolamine) dissolved in water, precipitation occurred; accordingly, the alkaline zinc-iron plating bath of Comparative Example 3 could not be prepared. On the other hand, the alkaline zinc-iron plating baths of Examples 1 to 53 and the alkaline zinc-iron plating baths of Comparative Examples 1, 2, and 4 to 14 could be properly prepared without causing precipitation.

Then, using the alkaline zinc-iron plating bath thus prepared, a hull cell test was carried out according to the conditions described below. The film thickness (μm) of the plating film and the eutectic rate of iron (%) were measured at any of 0.5 ASD (A/dm²: Ampere per Square Decimeter), 1 ASD, 3 ASD, 5 ASD, 8 ASD, and 10 ASD.

Tester Yamamoto-MS Tester Hull Cell Vessel

Cathode: SPCC material

Anode: C1220P material

Current: 1 A (8 ASD, 2 A at 10 ASD)

Testing time: 20 minutes (8 ASD, 10 minutes at 10 ASD)

Bath temperature: 30° C.

Stirring: not done

Film thickness and eutectic rate measurement instrument: X-ray fluorescence analyzer EA-6000VX; Hitachi High-Tech Science Corp.

The measurement results of the film thickness (μm) of the plating film obtained under the above conditions are described in FIG. 16 to FIG. 24 , and the measurement results of the eutectic rate (%) of iron are described in FIG. 25 to FIG. 33 . Measurement results of the film thickness (μm) of the plating film of Example and Comparative Example using the same raw materials except for the complexing agent are combined, which are illustrated by the graphs. These graphs are described in FIG. 34 to FIG. 86 . The measurement results of the eutectic rate (%) of iron of the same are illustrated by the graphs; and these graphs are described in FIG. 87 to FIG. 139 . In the alkaline zinc-iron plating bath of Comparative Example 3, the plating bath could not be prepared because of the precipitation occurred during the course of preparing the bath; accordingly, neither the film thickness (μm) of the plating film nor the eutectic rate (%) of iron was measured.

As can be seen in FIG. 34 to FIG. 86 , even when any of the iron ion concentration, the iron metal salt, and the molar ratio of the metal to the complexing agent is changed, the plating film in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is thicker as compared to the film thickness of the plating film in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent. In particular, with increase in the iron ion concentration, the film thickness of the plating film in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is thicker as compared to the film thickness of the plating film in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent. From this, by using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose, namely, by using the aliphatic compound having five or more hydroxy groups, it is possible to efficiently form a thick plating film. In other words, by using the aliphatic compound having five or more hydroxy groups as the complexing agent, it is possible to improve the current efficiency of the alkaline zinc-iron plating bath.

With regard to the eutectic rate of iron, when the iron ion concentration is low (iron ion concentration: 0.35 g/L), the eutectic rate of iron in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose, and the eutectic rate of iron in the alkali zinc-iron plating bath using triethanolamine as the complexing agent are almost constant independent of the current density (ASD). On the other hand, when the iron ion concentration is high (iron ion concentration: 9 g/L), the eutectic rate of iron in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is almost constant independent of the current density (ASD), but the eutectic rate of iron in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent varies greatly depending on the current density (ASD). Specifically, the difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent is 6.4 to 45.3, while the difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is 0.8 to 41.2. In particular, the difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using sodium gluconate or D-sorbitol as the complexing agent is 0.8 to 7.5. That is, the smallest difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is 0.8%, while the smallest difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent is 6.4%. In addition, the largest difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is 41.2%, while the largest difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent is 45.3%. In particular, the largest difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using sodium gluconate or D-sorbitol as the complexing agent is 7.5%. In addition, the difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose is about 4 or less, while the difference in the eutectic rates of iron in the alkaline zinc-iron plating bath using triethanolamine as the complexing agent is about 15 or more. Accordingly, by using, as the complexing agent, any of sodium gluconate, xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose, that is, by using the aliphatic compound having five or more hydroxy groups, even when the iron ion concentration is high, the eutectic rate of iron can be made constant independent of the current density.

In addition, as can be seen in FIG. 93 to FIG. 95 , even in the alkaline zinc-iron plating bath (Examples 7 to 9) with the iron ion concentration of 1.3 to 6 g/L, the difference in the eutectic rates of iron is about 3% or less. Therefore, in the alkaline zinc-iron plating bath with the iron ion concentration of 1.3 g/L or more, by using sodium gluconate as the complexing agent, it is possible to reduce the difference in the eutectic rates of iron independent of the current density. Considering the above-described results, even when any of xylitol, sorbitol, mannitol, glucose, fructose, lactose, and maltose, as well as sodium gluconate, is used as complexing agent, in the alkaline zinc-iron plating bath with the iron ion concentration of 1.3 g/L or more, it may be presumed that the difference in the eutectic rates of iron can also be reduced independent of the current density.

In the alkaline zinc-iron plating bath of Examples, the molar ratio of the metal containing zinc and iron to the complexing agent is set at 1:1 to 1:5. However, considering the error, by setting the molar ratio to the complexing agent at 1:0.5 to 1:5, it is possible to reduce the difference in the eutectic rates of iron independent of the current density.

All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention.

Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention. 

1. An alkaline zinc-iron plating bath comprising: a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent, wherein the complexing agent is an aliphatic compound having five or more hydroxy groups.
 2. The alkaline zinc-iron plating bath according to claim 1, wherein the complexing agent is at least any one of sorbitol, xylitol, sodium gluconate, mannitol, glucose, fructose, lactose, and maltose.
 3. The alkaline zinc-iron plating bath according to claim 1, wherein 0.02 to 20 g/L of an iron ion is contained therein.
 4. The alkaline zinc-iron plating bath according to claim 1, wherein when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5 to 10 ASD is 8% or less.
 5. The alkaline zinc-iron plating bath according to claim 1, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 6. The alkaline zinc-iron plating bath according to claim 2, wherein 0.02 to 20 g/L of an iron ion is contained therein.
 7. The alkaline zinc-iron plating bath according to claim 2, wherein when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5 to 10 ASD is 8% or less.
 8. The alkaline zinc-iron plating bath according to claim 3, wherein when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5to 10 ASD is 8% or less.
 9. The alkaline zinc-iron plating bath according to claim 6, wherein when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5 to 10 ASD is 8% or less.
 10. The alkaline zinc-iron plating bath according to claim 2, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 11. The alkaline zinc-iron plating bath according to claim 3, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 12. The alkaline zinc-iron plating bath according to claim 6, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 13. The alkaline zinc-iron plating bath according to claim 4, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 14. The alkaline zinc-iron plating bath according to claim 7, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 15. The alkaline zinc-iron plating bath according to claim 8, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.
 16. The alkaline zinc-iron plating bath according to claim 9, wherein a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5. 